Day 10: Charts & Data Visualisation

A bar chart (horizontal bars) or column chart (vertical bars) is the standard for category comparisons. Use column charts when you have few categories (under 7) with short labels. Use bar charts when category names are long (more than 15 characters) — they display more clearly on horizontal orientation. Never use 3D versions — they add visual distortion without information. Avoid pie charts for more than 4 categories.

A line chart is the standard for time-series data. Plot dates on the X axis and values on the Y axis. Use markers (dots at each data point) when you have few time points (weekly or monthly). Remove markers when you have many points (daily data). For multiple metrics over time, use multiple lines — not multiple bar groups, which become hard to read with more than 3 series.

A combo chart displays two different chart types on the same axes — typically a column chart on the primary axis and a line chart on a secondary axis. Classic use case: showing revenue (columns, left axis) and profit margin percentage (line, right axis) on the same chart. The two Y axes allow metrics with very different scales to be shown meaningfully side by side. Create via Insert → Chart → Combo.

Right-click the chart series → Add Data Labels. Then right-click the labels → Format Data Labels to choose position (above, inside, centre), what to show (value, percentage, category name), and number format. For clean presentation: show only the labels you need (not every data point in a dense line chart — just the start, end, and key points), format numbers appropriately (₹1.2L, not 120000), and ensure font size is readable (minimum 9pt).

Sparklines are tiny charts embedded within a single cell — not a standalone chart object. Insert → Sparklines → choose Line, Column, or Win/Loss. They show the trend or pattern for a row of data in a compact format, useful in summary tables where you want a quick visual indicator next to each row of data without taking up chart space. Example: a monthly sales summary table with a tiny line sparkline in the rightmost column showing each product's trend.